Eric,
If I'm not mistaken, the 35 spline 9" shaft has no body to neck down. It's pretty much the same diameter right up to the bearing journal. Moser has always been a top notch shaft but I am open to suggestions.

My point is that the shaft should have neck down in the center. The splined area should not be the weakest area. It concentrates the stress in the splined area instead of distributing among a larger area. An axle shaft should be designed to twist similar to a torsion bar.

My point is that the shaft should have neck down in the center. The splined area should not be the weakest area. It concentrates the stress in the splined area instead of distributing among a larger area. An axle shaft should be designed to twist similar to a torsion bar.

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This is correct from my experiance also. If the shaft was necked the entire length of the shaft and back to bigger at the splines it allows the shaft to twist causing less breaks. Actually Jack from CTM was the first to explain that to me when I was building my buggy that had little baby shafts in it.

I agree. If the entire axle shaft is the OD of the spline, the weakest point is the pitch diameter of the spline. Since the pitch diameter (in this case) is only about 3" long, all torsional windup must happen in that area. If it is longer, there is less chance of the shaft yielding. I have used long bolts in some designs for this same reason. What (good quality) manufacturer does this? I'm not stuck on Moser.

Eric,
If I'm not mistaken, the 35 spline 9" shaft has no body to neck down. It's pretty much the same diameter right up to the bearing journal. Moser has always been a top notch shaft but I am open to suggestions.

When I last talked to Moser at a trade show they said they would look at doing neck down shafts for my 10 bolt. However I was under the impression that I had to provide the required measurements. Although with yours being a 9" I'd assume they would already have something drawn up that could be transferred to your custom shafts.

Another option to look into would be gun drilling the shafts. As my grandfather’s dragster used to run 35 spline semi float shafts that were gun drilled (from Moser) for years of racing with 1,xxxhp, 6.00 r&p, 36x17" supper scoops, and a spool. All with zero shaft failures and no spline deformation.

I've ran a full detroit in the back of two daily driven TJ's, once with an auto, and once with a stick.

With the auto it was absolutely smooth as silk, I really had no issues with it, and I could take someone for a ride and they'd never know it was locked.

The stick was a slightly different story, it was more noticeable, but I wouldn't call it terrible.

Point being is that I drove these things daily, I could make turns, pull out into traffic, accelerate in turns etc. With that said however, it was all based on the throttle - if I jammed on the gas while making a turn, it would lock up and squeal a tire.

I don't know much about the grizzly, but if it's anything like a Detroit I think you will really be pleased - it has to be ten times better than a full spool - both off and on road.

That Jantz thread is interesting, as all of his threads are. The thing is, he is an engineer's engineer and is pushing to the extremes; which is good for advancing the sport and building the ultimate gizmo, but not always great on the pocket book.

Moser (and many other custom shaft makers) that are selling to sportsman and hobbyists build shafts by cutting splines and polishing a bearing surface. The main thing they are trying to do is keep costs down by doing as little rework to a blank as possible. They go for strength using brute force.

Jantz, Trophy truck teams, and other well heeled individuals go the extra step and build shafts with proper length rolled/hobbed splines, and turn down the shaft to the minor diameter and produce beautiful machined pieces with rolled edges, blah blah blah to maximize strength vs weight; and in some cases like the story about the Ivan Stewart truck, provide desired amounts of cushioning to the drive line to make the axle shaft the fuse to protect other components.

Since OEMs build by the 1000s, they can also afford to build shafts "the right way" since they can spread the cost over many parts.

Given that you've gotten 6 years out a set of shafts, I'd say brute force is working for you. If you manage to destroy these in short order, then it might be time to call up Jantz.

And don't they have a lifetime warranty of Moser 35-spline shafts? I thought my 40-spline stuff (even more brute force) did.

All good points John. No, Moser will not warranty an off road application, only drag racing. Go figure. I would also be more concerned if both splines were twisted, and since only one has moved, it's another good indicator that I don't have a design problem.

I just got through cleaning the ring gear up. It is definitely not just a chip, it's into the wear pattern & about half the tooth is gone in one spot. I talked to Hi-9 today and sent them a pic, they felt it was a shock load break. I have no idea where the "event" could have happened other than my parking lot episode. My only other major catastrophic issue has been my broken link in Cali, but I don't think that should have stressed the gears.

Hi-9 used to not sell gear sets because they wanted to assure they were set up properly in the beginning. Now they sell them outright so it looks like I will be tapping Dale on the shoulder for his expertise.

That Jantz thread is interesting, as all of his threads are. The thing is, he is an engineer's engineer and is pushing to the extremes; which is good for advancing the sport and building the ultimate gizmo, but not always great on the pocket book.

Moser (and many other custom shaft makers) that are selling to sportsman and hobbyists build shafts by cutting splines and polishing a bearing surface. The main thing they are trying to do is keep costs down by doing as little rework to a blank as possible. They go for strength using brute force.

Jantz, Trophy truck teams, and other well heeled individuals go the extra step and build shafts with proper length rolled/hobbed splines, and turn down the shaft to the minor diameter and produce beautiful machined pieces with rolled edges, blah blah blah to maximize strength vs weight; and in some cases like the story about the Ivan Stewart truck, provide desired amounts of cushioning to the drive line to make the axle shaft the fuse to protect other components.

Since OEMs build by the 1000s, they can also afford to build shafts "the right way" since they can spread the cost over many parts.

Given that you've gotten 6 years out a set of shafts, I'd say brute force is working for you. If you manage to destroy these in short order, then it might be time to call up Jantz.

And don't they have a lifetime warranty of Moser 35-spline shafts? I thought my 40-spline stuff (even more brute force) did.

I 100% agree. The only thing is that he has only been running the stickies for only about half that time. If you want to keep running the stickies I would suggest investing in better shafts. If you end up going to a regular compound tire then run the Mosers.

I have to disagree. Yes, I haven't been running the stickies that long, but I have been running them for 3-4 years. And, as in any engineering failure, you look for events if possible, rather than not knowing what caused a problem. I can pinpoint a very specific event that had enough torque on my driveshaft to twist a heavy duty Tom Woods spline. As debated over and over above, maybe the locker will solve that problem, maybe it won't, but I am making one specific move to change the dynamics.

I am also much more aware of the potential problem and can hopefully drive around it some. Noting the Jantz thread, no one has offered up any super duper shafts that aren't expensive custom made like Eric Miller is running.

Back to the Moser concept of bigger is better, I have mixed feelings about it. We make induction hardened shafts that have splines on the ends and I am very familiar with the heat treatment and processes. I also have first hand experience with a longer torsional shaft versus a shorter one. But, if the Moser tests are correct that a smaller diameter shaft "IS" weaker than the minor diameter of a spline, eventually it can fail too. And, it makes sense. Yes it can torsionally wind up more than the spline, but once it meets its yield point, either it will fail or the spline will fail.

One other note, the Moser tech told me that a spline has not failed if it has not twisted more than 1-1/2 spline teeth. I find this questionable but he told me most splines will move some. I am not the expert on this and I feel comfortable with the answers from Moser.

One other note, the Moser tech told me that a spline has not failed if it has not twisted more than 1-1/2 spline teeth. I find this questionable but he told me most splines will move some. I am not the expert on this and I feel comfortable with the answers from Moser.

I hope they mean over the length of the entire shaft and not the pictured spline....

Edit...I just looked again and I agree that yours is still probably "good". Thinking of another picture that had the twist in about a quarter inch section.

I guess I didn't pin him down but to me, it's stressed more than it should be and from a metallurgical standpoint, there's no fixing it. Not knowing the specifics the material & heat treat, we don't know specifically what temps to stress relieve it at. But in most cases, stress relieving causes distortion in other areas. So, it gets stored as a spare.

The new Grizzly locker is in thanks to Dale @ Ironman. Thanks Dale for setting up my gears. My first reaction is wow, is that thing noisy. It sure goes clickety clack. But it works. I find that it releases when coasting around a corner with no problem. I did a whole bunch of playing around on an asphalt parking lot doing tight turns both directions, forward and reverse. It released without any effort. It also releases when under power when I am just maintaining speed. Give the throttle a blip and it locks in. I'm guessing it's going to take some getting used to but it seems to do what I was hoping for.